“Robin's sobriety was intact and he was brave as he struggled with his own battles of depression”

Susan Schneider, Robin Williams' wife

Williams' wife Susan Schneider told the world that her husband had been diagnosed with the illness and was battling with the early stages of the condition.

She also insisted the Oscar winner was sober when he died but toxicology tests are yet to confirm.

She said: "Robin spent so much of his life helping others. Whether he was entertaining millions on stage, film or television, our troops on the frontlines, or comforting a sick child - Robin wanted us to laugh and to feel less afraid, she said.

"Since his passing, all of us who loved Robin have found some solace in the tremendous outpouring of affection and admiration for him from the millions of people whose lives he touched.

"His greatest legacy, besides his three children, is the joy and happiness he offered to others, particularly to those fighting personal battles.

"Robin's sobriety was intact and he was brave as he struggled with his own battles of depression, anxiety as well as early stages of Parkinson’s disease, which he was not yet ready to share publicly.

"It is our hope in the wake of Robin’s tragic passing, that others will find the strength to seek the care and support they need to treat whatever battles they are facing so they may feel less afraid."

There are five stages of Parkinson's disease with the condition developing gradually over time.

Stage one begins with mild symptoms of muscle stiffness and tremors in certain parts of the body before it moves through to other areas.

As it develops, patients begin to lose movement in both sides of their body, making it difficult to walk.

TESTS: His wife told the world that Robin was sober when he died [AP]

Just hours before the statement emerged from his wife, Williams' former spokeswoman denied rumours the 63-year-old had been going through financial difficulties.

She wrote in an email to NBC News: "Reports suggesting Robin may have had financial issues are simply false,' Mara Buxbaum said in an email to NBC News.

"I understand people's desire to try to understand this, but we would encourage your focus be on working to help others and understand depression."

It is believed that Williams' found comfort over the years in his beloved pug Leonard Bean.

He posted dozens of photos of him and his best pal suggesting the fun-loving actor we once knew was much more reserved and inside himself by the end.

He said in an interview earlier this year: " I have a gay rescue pug called Leonard, who I take for walks because I am very secure in my sexuality.

"He has a boyfriend and they are planning to adopt a Siamese kitten together. We're very modern."

Personal assistant Rebecca Erwin, who found him dead on Monday, is now looking after Leonard.

The star had hanged himself after years of battling severe depression and troubles with drugs and booze in the past.

He was admitted to rehab last month after friends said he was taking on acting roles he didn't want, just to help out financially.